Several laboratories have developed monoclonal antibodies (MAbs) or immunoassays for monitoring the expression of the two well-characterized prostate antigens, i.e., prostatic acid phosphatase (PAP) (Chu et al., in T. M. Chu, ed., Biochemical Markers for Cancer, pp. 117-128, New York, Marcel Dekker, Inc., 1982; Taga et al., 1983, Prostate 4:141-150) and prostate-specific antigen (PSA) (Wang et al., 1979, Invest. Urol. 17:159-163). Neither of these prostate markers, however, has been found useful for early detection or for distinguishing benign from malignant prostate tumors. Moreover, these prostate markers do not provide meaningful information regarding the progressive nature or aggressiveness of the tumor.
Additional MAbs that have shown potential for detecting circulating prostate antigens in patient serum include TURP-27 (Starling et al., 1986, Cancer Res. 46:367-374), 7E11-C5 (Horoszewicz et al., 1987, Anticancer Res. 7:927-936) and PR92 (Kim et al., 1988, Cancer Res. 48:4543-4548). These antibodies recognize tumor antigens that are either prostate-organ specific, such that they react with normal and benign prostate antigens as well as carcinoma, i.e., PSA, PAP, 7E11-C5 and TURP-27, or they cross-react with non-prostate cells or carcinoma, i.e., PR92 cross-reacts with breast carcinomas.
U.S. Pat. No. 5,055,404 issued Oct. 8, 1991 to Ueda et al., describes monoclonal antibodies which recognize "differentiated antigen" specifically found on epithelial cells of human prostate including normal prostate, benign prostatic hyperplasia and prostatic cancer.
Two monoclonal antibodies described by Bazinet et al., (1988, Cancer Res. 48:6938-6942) recognize an antigen that is selectively expressed on malignant prostatic epithelium. However, these MAbs appear to identify only a small reactive subset of prostate carcinomas provided the tissue specimens have not been exposed to fixatives.
At present, there still remains a definite need for the identification of other prostate tumor associated antigens. In particular, there is a need for MAbs which preferentially bind to prostatic carcinoma and show little or no cross-reactivity to benign prostatic hyperplasia and normal prostatic epithelia. Such antibodies will be useful for both diagnosis and therapy of prostate carcinoma. Additionally, there is a need for MAbs specific for prostate carcinoma, that will be useful for early detection and monitoring of prostatic carcinoma disease and progression and/or which can provide additional clinical and pathological information with respect to aggressiveness or metastatic potential of prostate carcinoma.